Treatment of rubber



Patented Oct. 31, 1944 UNITED STATES .ATENTI OFFICE TREATMENT or RUBBER-Edwin J. Hart, Cedar Grove, N. J., and Robert/T. Armstrong, New York, N.M, assignors to United States Rubber Company, New York, N. Y.,acorporation of New Jersey N0 Drawing. Application November 6, 1941,Serial No. 418,042

17 Claims.

This invention relates to the treatment of rubber and similaroxidizablematerials and more particularly to a new class ofdeterioration retarders.

This application is a continuation-impart of our application Serial No.--332,780, filed May '1,

-An object of "this invent-ion is to provide a new class ofanti-oxidants or age resisters for organic substances which tendtodeteriorate by absorption of oxygen from the air, for example goods ofrubber or allied gums, unsaturated fatty oils, petroleum oils such asgasolines, soaps, aldehydes, synthetic resins, turpentine and the like.A further object is to provide chemicals which show little or nodiscoloration of the surface of a rubber composition containing them,-onexposure to sunlight. Further objects will be apparent from thefollowing description.

Broadly, the invention comprises the incorporation in rubber and thelike as aforesaid, of a member of the class consistin of compoundsrepresented by the formula:

where Ar and Ar are aromatic groups; Y represents a hydrocarbon radical;X is a member of the group. consisting 'of hydrogen and b ase-formingradicals. By base-forming radicals meant an element normally formingsaltswith acids, such :as zinc, calcium, magnesium, sodium, ammonium,=dimethylammonium and :the like. Among such compounds are thearylaminoaryloxyaliphatic acids,.ar-ylamino ar-yloxy aromatic acids, arylamino'aryloxy arylalkyl :carboxylic acids, and the lmetal, :ammonium, and:alkyl ammoniumsalts thereof. The acids :may contain one ormoreparboxylic acid groups, where used ialoneyor for preparationof thesalts which :are

to be :used. Byarylgroup ismeans an .aromatic hydrocarbon radical,further substituted :o :not

asby alkyl or hydroxy groupsgand.havingsa :fliee valence belonging tothe :aromatic nucleus.

The useful chemicals are further illustrated by the following examples:

H v I 1 mONQ-o-cHhcooH COOH -I O-o-g-xonm-ooon The chemicalsrmay bepreparedxby-well-known 'methods, such as, for example, -by'the-interaction of a hydroxy-diarylamine and a halogen substitutedorganic acid, in the ,presence of alkali.

The zinc salts may be madeby .mixinga water solution of an equivalentamount of the sodium salt of the chemical with a water solution of zincsulfate. The zinc salt precipitates.

The chemicals may be used in the pure state or as crude products ofreaction. The following table lists some of the physical properties ofsome of the pure chemicals:

Neutralization Nitrogen Melting equivalent analysis point Found Theo.Found Theo.

p-Anilinophenoxy "O. acetic acid 146-147 ID-p-anilinophenoxy undecylicacid 66-67 ll-p-anilinophenoxy undecylic acid 108-109 .341 369 4.0 3.8 B(p-Anilinophenoxy) propionic acid 129-130 250 p-(i-carboxybenzy-1oxy)-diphenylamine 189191 169 l-(B-naphthylaminophenoxy)-undecylic acid87-88 Commercially available acids may be used, as, for example, oleicacid. By hydrobromination followed by reaction with p-hydroxydiphenylamine in the presence of alkali a crude reaction product isobtained containing a mixture of 9- and l0-p-anilinophenoxy stearic acidas well as small amounts of neutral impurities. One such product had aneutralization.equivalent, found 550, theory 467, and a nitrogenanalysis, found 2.6%, theory 3.0%, and was a dark viscous oil.

The zinc salts of the above compounds are particularly useful in milledrubber, and ammonium or alkyl ammonium salts in latex.

The compounds are especially useful in rubber, in amounts varying from0.1%"to 3% by weight, based on the rubber. An additional advantage liesin the fact that these compounds do not bleed from the rubber andthereby cause discoloration of lacquers, fibers, etc., in contact withthe rubber containing the antioxidant. Also, these chemicals are lessreadily'extractable by organic solvents, such as thoseused in'dry-clean-' ing, than are other common antioxidants.

The following examples, in which the parts are by weight, illustrate theage-resisting properties of the chemicals conveyed onto typical whitestocks: 1

Example. 1 r

100 100 100 5 5 30 30 30 111 u! 3 3 3 Tetramethyl thiuram .monosulfide0. 1 0. 1 0. l p-Anilinophenoxy acetic acitL. 1. 0 Zinc salt ofp-anilmophenoxy acetic acid 1. 0 Green tensile and Stretch: T E T E T Emin. at 116 0 3,900 780 3, 500 820 3, 400 820 45 min. at 116 O 3, 400780 3, 200 830' 3,400 770 60 min. at 116 C 3, 500 830 3,100 810 3,400800 120 hrs. oxygen bomb and stretch:

30 min. at 116 C 886 670 l, 500 800 1, 900 800 45 min. at 116 C 1 P 1,200 760 1, 200 780 00 min. at 116 C 1 P 877 680 1,000 680 240 hrs.oxygen bomb tensile I i and stretch:

30 min. at 116 C- 1 P 376 750 474 p 610 45 min. at 116 C. 1 P 193 420224, 470 60 min. at 116 C- 1 P 145 360 161 .400

1 P-Too poor to tensile. 1 T=tensile strength in lbs. per sq. inch.

E=ultimate elongation.

Example 2 Pole crepe 100 100 100 Zinc oxide 10 10 10 Whiting.- 60 60 60Lithopone 60 6O 60 Zinc soap of ds 0.5 0. 5 0. 5 Sulfur f.-. 3.0 3.0 3.0Tetramethyl thiurarn mono- 0. 0.15 0.15

sulfide. p-Anilinophcnoxy acetic acid 1. 0 l0-(p-anllmophenoxy) undecy-1.0

lic acid. Green tensile and stretch: T E T E T E 10 min. at 122 2, 400700 2, 000 630 2, 100 650 m n. at 122 0 2, 400 690 2, 300 000 2, 300 680min. at 122 0 -1 2, 400 800 2, 660 1, 900 670 72 hrs. oxygen bombtensile and stretch:

10 min. at 122 0 1,700 610 1, 900 620 2,100 000 20 min. at 122 C 327 2201, 300 520: 1, 400 670 30 mm. at 122 C 1 P 865 530 1, 100 030 hrs.oxygen bomb and stretch:

l0 at 122 C 402 370 1,400 590 1,800 620 20 min. at 122 C l P 752 510 1,300 590 30 mm. at 122 C l P 368 270 l, 200 610 240 hrs. oxygen bombtensile and stretch: a 10 at 122 C l P 651 470 1, 700 020 20 mm. at 122C. l P 256 390 1, 200 580 30 min. at 122 C l P 1 P 808 510 1 PToo poorto tensile.

Example 3 Pale crepe 100 Zinc oxide 10 Lithopone 60 Whiting 60 Zinc saltof cocoanut fatty acids 0.5 Sulfur 3.0 Tetra methyl thiuram monosulfide0.15

To separate portions of the above stock, the indicated number of partsby weight of the following chemicals were added per one hundred parts ofrubber on a mill at F., and slabs 0.1

inch thick were cured in a mold for 20 and 30 minutes at 122 C. with thefollowing results:

p-(i-carboxy-benzyloxy) -diphenylamine 0.5 1 p-(p-Anilinophenoxy)propionic acid 0.5

Green: T E T E 20 min. at 122 C 2,300 7.1 2, 800 6.8 30 min. at 122 C2,100 7. 1 2, 000 7. 0

Aged 120 hrs. in oxygen bomb:

20 min. at 122 C 501 4. 5 1, 200 6. 0 30 min. at 122 G 284 3. 3 755 5.8Aged 240 hrs. in oxygen 20 min. at 122 C 319 2.5 470 4. 6 30 min. at 1220.. 345 3. 4

1 P-loo poor to tensile. T=tensi1e strength in lbs. per sq. inch.E=ultimate elongation.

The invention may be applied to the preservation of natural as well asartificially prepared rubbers, including reclaims and latices of suchrubbers.

It is also to be understood that other desired filling and compoundingingredients may be incorporated along With-the preservative, forexample, in the case of rubber, there may be incorporated otheraccelerators, softeners, etc.

The antioxidant may be incorporated in any type of rubber composition,such as those used for automobile tires and tubes, hose, belting, sheetand thread rubber, rubberized fabrics, molded goods, boots and shoes,etc., whether vulcanized in a mold, in open steam, in hot air, or in thecold by the so-called acid process. The proportion of the antioxidantmay vary from about 0.1% to 3% although either smaller or greaterproportions may be found useful. If the material to which it is added isa liquid such as rubber cement or an oil the antioxidant may bedissolved therein in a suitable small proportion. The antioxidant maybeincorporated into solid.

substances by milling or mastication, and prepared for incorporationinto dispersionsor solutions either in powder, paste or solution form,or applied in such forms for incorporation by diffusion, to the surfacesof vulcanized or unvulcanized rubber goods.

Having thus described our invention, what we claim and desire to protectby Letters Patent is:

1, A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air, which comprises incorporatingtherein a compound having the general formula ArNIIAr'OY-COOX Where Aris an aryl group; Ar is an arylene group; Y is a hydrocarbon radical; Xis a member of the group consisting of hydrogen and base-formingradicals.

2. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein an arylamino-aryloxy-aliphatic hydrocarbonoic acid in which thealiphatic hydrocarbon group is saturated.

3. A. method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein a metal salt of an arylamino-aryloxyaliphatic hydrocarbonoicacid in which the aliphatic hydrocarbon group is saturated.

4. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein an anilinophenoxy hydrocarbonoic acid.

5. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein an anilinophenoxy aliphatic hydrocarbonoic acid in which thealiphatic hydrocarbon group is saturated.

6. A method of preserving organic substances which tend to, deteriorateby absorption of oxygen from the air which comprises incorporatingtherein an anilinophenoxy aromatic hydrocarbonoic acid.

7. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein a zinc salt of an anilinophenoxy hydrocarbonoic acid.

8. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein a zinc salt of 10-(p-anilinophenoxy) undecylic acid.

9. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein IO-(p-anilinophenoxy) undecylic acid.

10. A method of preserving rubber which comprises incorporating thereina compound having the general formula where Ar is an aryl group; Ar isan arylene group; Y is a hydrocarbon radical; X is a member of the groupconsisting of hydrogen and baseforming radicals.

11. A method of preserving rubber which comprises incorporating therein10-(p-ani1inophenoxy) undecylic acid.

12. Rubber containing a compound having the general formula ArNHArOYCOOX where Ar is an argyl group; Ar is an arylene group; Y is ahydrocarbon radical; X is a member of the group consisting of hydrogenand baseforming radicals.

13. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air, which comprises incorporatingtherein a compound having the general formula Ar-NI-I--Ar'OY-COOX whereAr is an aryl group; Ar is an arylene group; Y is a saturatedhydrocarbon radical; X is a member of the group consisting of hydrogenand base-forming radicals.

14. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air, which comprises incorporatingtherein an anilinophenoxy hydrocarbonoic acid in which the hydrocarbongroup attached to carboxyl is saturated.

15. A method of preserving organic substances which tend to deteriorateby absorption of oxygen from the air which comprises incorporatingtherein a zinc salt of an anilinophenoxy hydrocarbonoic acid in whichthe hydrocarbon group of the hydrocarbonoic group is saturated.

16. A method of preserving rubber which comprises incorporating thereina compound having the general formula where Ar is an aryL group; Ar isan arylene group; Y is a saturated hydrocarbon radical; X is a member ofthe group consisting of hydrogen and base-forming radicals.

1'7. Rubber containing a compound having the general formulaArNHAr'O-YCOOX where Ar is an aryl group; Ar is an arylene group; Y is asaturated hydrocarbon radical; X is a member of the group consisting ofhydrogen and base-forming radicals.

EDWIN J. HART. ROBERT T. ARMSTRONG.

